We have made progress in the following research areas: 1) We have shown that dB-cAMP stimulates dopamine biosynthesis in striatal brain slices and synaptosomal preparations. The results of our studies have shown that the cyclic nucleotide reduces the feedback inhibition of tyrosine hydroxylase and these effects might be due to an allosteric activation of the enzyme. 2) We have purified bovine and humaa tyrosine hydroxylase as well as human dopamine-Beta-hydroxylase. The purified enzymes were used as antigens for production of antibodies in rabbits. The antibodies were used for measuring serum dopamine-Beta-hydroxylase by a specific radioimmunoassay and for mapping monoaminergic neurons in the CNS. 3) We have mapped out phenylethanolamine N-methyltransferase (PNMT) containing neurons with immunohistological techniques and with an enzymatic procedure. The PNMT containing neurons were localized in the medulla oblongata and in nerve terminals in special nuclei of the brain stem and spinal cord. The distribution of PNMT neurons suggest that they may play an important role in the control of certain brain functions.